Previously, transport devices for letters and the like, comprising a switching device generally comprised a resilient or pivoting tongue, which was directed against or away from the stream of letters. These types of switching tongues were held in a normal position such as by a spring and were driven into their switching or operating positions by various known electric or pneumatic means. The drawbacks of these switching tongues are slowness, vulnerability and the possibility of blocking. Another type of switching device comprised a conveyor-belt part which is projected into a path by means of a movable roller. The working of this type too is slow, and the conveyor-belt must be of an elastic kind which is always subject to an excessive wear.